Whole-body PET/CT scans reveal metabolic shifts in multiple organs following bariatric surgery, according to a new study. The findings suggest that weight loss after procedures like sleeve gastrectomy or gastric bypass triggers coordinated changes across the body, affecting everything from fat tissue to the liver and muscles. Researchers presented the results at the Society of Nuclear Medicine and Molecular Imaging 2026 Annual Meeting, highlighting the potential for more precise post-surgery monitoring.
The study tracked 32 patients who underwent either laparoscopic sleeve gastrectomy or one-anastomosis gastric bypass. Each participant had whole-body 18F-FDG PET/CT scans before surgery and again one year later. These scans measured metabolic activity in organs including the liver, pancreas, spleen, adrenal glands, and skeletal muscle. The data were compared to scans of healthy individuals and analyzed for patterns in metabolic changes.
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Results showed significant reductions in subcutaneous and visceral fat, as well as changes in organ volume and metabolic activity. The liver, pancreas, and spleen showed decreased 18F-FDG uptake, while skeletal muscle volume declined. At the same time, the colon appeared larger in some patients during follow-up scans. These shifts correlated with improvements in blood markers related to glucose, lipids, and inflammation.
“Currently, clinicians do not have a clear way to see how the body’s metabolism changes after bariatric surgery,” said Zeyang Wang, a PhD candidate at the Medical University of Vienna. “Having a full understanding about the changes happening across multiple organs would provide valuable data for follow-up care.” The study’s authors argue that traditional weight loss metrics and blood tests miss much of the body’s response to surgery.
Network analysis of the metabolic data revealed stronger connections between organs after surgery. This suggests that the body’s systems become more synchronized in their function, possibly reflecting a broader reorganization of energy use and tissue repair. The findings challenge the common view that bariatric surgery’s benefits are limited to weight loss alone.
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The research highlights the complexity of post-surgery recovery. While weight loss is a primary goal, the study shows that metabolic changes extend beyond the digestive system. For example, the liver’s reduced metabolic activity may contribute to improved glycemic control. These insights might help doctors tailor follow-up care for individual patients.
Experts note that the study’s use of whole-body imaging provides a more complete picture than conventional methods. “Molecular imaging may help show how different organs respond after surgery, beyond what can be measured by weight loss or blood tests alone,” Wang said. The approach could also help identify patients at risk for complications, such as muscle wasting or imbalances in organ function.
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Despite the promising results, the study’s small sample size and focus on a specific group of patients—those undergoing two types of bariatric procedures—limit its broader applicability. Future research may explore how these metabolic changes vary across different surgeries, patient demographics, and long-term health trajectories.
The findings add to a growing body of evidence that bariatric surgery is more than a tool for weight control. It’s a complex intervention that reshapes the body’s metabolic setting in ways that are only beginning to be understood. For now, the study offers a new way to visualize these changes, potentially improving how clinicians support patients during recovery.